Scientists have found convincing evidence to support the idea that the "fat gene" affects how hungry someone feels, which has a direct effect on how much food is eaten and how much fat is accumulated in the body. The study was carried out on genetically modified mice with several copies of the fat gene added to their DNA. The scientists said the findings support the idea that the gene in humans plays a direct role in determining whether someone is likely to become obese. ... Women are affected more than men, with a third of women and half of men classified as overweight, which carries an increased risk of heart disease, cancer and diabetes.